In particular, the invention concerns the dispensing of preservative-free liquid, in the form of drops, using a deformable reservoir with air intake.
The current trend is to supply products, especially ophthalmic products, that do not contain preservatives. The sterility of the product must thus be guaranteed throughout the use of the bottle containing the liquid to be delivered.
From document WO92/01625, various devices are known that enable the delivery of drops of product contained in a reservoir and which prevent contamination of the liquid remaining in the bottle.
According to one example, such a liquid-dispensing device includes a reservoir and a dispensing end piece fitted on the reservoir, provided with a liquid-dispensing opening. The user applies pressure to the reservoir causing it to become deformed and, under the effect of pressure, a drop forms on the surface of the dispensing opening. Once the drop has been dispensed, the user releases the pressure on the deformable reservoir, which tends to take up its initial shape, generating a depression inside the bottle. To fill this depression and allow the reservoir to return to its initial shape, the end piece of the device comprises an air inlet in the reservoir. To ensure that the incoming air cannot contaminate the liquid remaining in the reservoir, a hydrophobic filter is fitted in the air channel. This filter allows the exterior air to enter the reservoir while avoiding the entry of microorganisms and dust, and preventing liquid from entering or leaving.
One problem with this type of device lies in the fact that it is difficult to guarantee its reliability. It is in fact difficult to test correct operation of the filter after fitting on the end piece, since the filter would have to be tested under water, which implies a risk of contamination or degradation during the test phase. It is therefore difficult to guarantee the integrity of the filters used and of their assembly on the end piece.
The present invention is intended to provide a device for dispensing liquid which reliably guarantees the sterility of the dispensing end piece.